Thursday (January 17) marks Michelle Obama's 55th birthday, and, of course, her famous friends and family couldn't help taking advantage of the very special occasion to share their love for the lawyer, author, and style star on social media. Perhaps most heartfelt among these celebratory posts were those from her husband, Barack Obama, and her good friend Beyoncé, both of whom opted to share throwback photos of the former first lady in honor of her birthday.

In his post, Barack wrote, "I knew it way back then and I'm absolutely convinced of it today—you're one of a kind, @MichelleObama. Happy Birthday!" The accompanying picture shows him and his wife in their younger days—sometime in the '90s, when they were in their late 20s or early 30s, judging by the wedding band visible on Barack's left hand in the photo and by the mention of Russian politician Mikhail Gorbachev in the newspaper he's holding.

Beyoncé, meanwhile, went even further back in time. She shared a black-and-white photo of Obama as a child, dressed in her Sunday best and carrying an Easter basket, and overlaid the words "Bow Down," in the same all-caps pink font from her eponymous 2013 album's cover, superimposed. Together, Beyoncé and Barack's posts have garnered several million likes, plus countless comments proving that Barack is far from the only person who believes the former First Lady is "one of a kind."

Beyond those two, dozens more stars also made sure to wish Obama a happy birthday on Twitter and Instagram. Among these were Pharrell, who called her a "living breathing inspiration for inevitable change"; and Christian Siriano, who dressed Obama several times throughout her time in the White House and her recent Becoming book tour, and wrote that "it is an honor to create for you!" Reese Witherspoon, who accompanied Obama to one of her book tour dates, and Shonda Rhimes, who wrote a "heartfelt review" of the book, also chimed in, with both sharing photos of them posing with Obama on their respective feeds.